Polyurethane foams stabilized against scorch with a mixture of butylated hydroxy toluene and p,p&#39;-dioctyl diphenyl amine

ABSTRACT

POLYURETHANE FOAMS ARE STABILIZED AGAINST SCORCHING WHEN A MIXTURE OF 2,6-DITERTIARY-BUTYL-4-METHYL PHENOL AND A P,P&#39;&#39;-DIALKYL DIPHENYL AMINE CONTAINING BETWEEN ABOUT 3 AND ABOUT 18 CARBON ATOMS IN THE ALKYL, IS PRESENT IN A FOAM FORMING REACTION MIXUTRE OF AN ORGANIC DIISOCYANATE, THE REACTION PRODUCT OF A 1,2-OXIDE AND AN ALIPHATIC POLYHYDRIC ALCOHOL CONTAINS BETWEEN 2 AND 6 HYDROXYL GROUPS AND 2 AND 8 CARBON ATOMS PER MOLECULE, A REACTGION CATALYST AND A FOAMING AGENT. THE PROPORTION OF THE AMINE IN THE STABILIZING MIXTURE IS BETWEEN ABOUT 15 AND 90 PERCENT BY WEIGHT.

".nited States Patent @5563 3,507,664 Patented Mar. 2, 1971 US. Cl.260-25 12 Claims ABSTRACT OF THE DISCLOSURE Polyurethane foams arestabilized against scorching when a mixture of2,6-ditertiary-butyl-4-methyl phenol and a p,p-dialkyl diphenyl aminecontaining between about 3 and about 18 carbon atoms in the alkyl, ispresent in a foam forming reaction mixture of an organic diisocyanate,the reaction product of a 1,2-oxide and an aliphatic polyhydric alcoholcontains between 2 and 6 hydroxyl groups and 2 and 8 carbon atoms permolecule, a reaction catalyst and a foaming agent. The proportion of theamine in the stabilizing mixture is between about 15 and 90 percent byweight.

This application is a continuation-impart of co-pending application Ser.No. 540,806, filed Apr. 7, 1966, by Robert C. Haring, now abandoned.

This invention relates to a process for stabilizing polyether polyolsand for stabilizing polyurethane foams and to the stabilizedcompositions produced thereby.

Polyether polyols are used extensively as a major reactant in thepreparation of polyurethane foams. Under certain conditions thesepolyether polyols are subject to oxidation which causes discoloring aswell as diminishing of the reactivity. In addition, one of the problemsencountered in the preparation of polyurethane foams is that the foambecomes scorched under certain reaction conditions, which severelydegrades the physical properties of the foams, even when prepared frompolyether polyols which are free from any significant oxidativedegradation. Furthermore, some polyurethane foams become discolored orscorched in a few hours when stored, especially when polyurethane foamslabs are stored in relatively high stacks. Storage of polyurethane foamslabs in this manner inhibits heat transfer from the interior of thefoam, particular from those slabs in the center of the stack, and as aresult, the high concentration of heat frequently causes discolorationand scorching.

It is an object of this invention to provide a novel stabilizing systemfor inhibiting polyether polyols against oxidation.

Another object of this invention is to provide polyether polyolsstabilized against oxidative degradation.

Still another object of the invention is to provide polyurethane foamstabilized against scorching.

A further object of the invention is to provide a novel stabilizersystem to inhibit scorching of polyurethane foams.

These and other objects of the invention will be apparent from thefollowing detailed description thereof.

It has now been discovered that the foregoing objects are accomplishedwhen a stabilizing proportion of a mixture of2,6-di-tertiary-butyl-4-rnethyl phenol and a dialkyl diphenyl amine isadmixed with a polyether polyol to inhibit oxidation thereof, and whenthe stabilized mixture is employed in the preparation of polyurethanefoams from a polyether polyol, an organic polyisocyanate, a foamingagent and a reaction catalyst.

In preparing the stabilizer system of this invention, the2,6-ditertiary-butyl-4-methyl phenol, which is referred to hereinafteras butylated hydroxy toluene, is admixed with a suitable p,p'-dialky1diphenyl amine. The alkyl moiety of the substituted amine containsbetween about 3 and about 18 and preferably between about 6 and about 10carbon atoms. Typical examples of suitable p,p-dia1kyl diphenyl aminesare as follows:

It will be recognized by those skilled in the art that the alkylsubstituents may not be the same on each phenyl group and that mixturesof alkyl substituents may be employed. For example, suitable compoundsinclude poctyl-p-dodecyl diphenyl amine and similar amines havingdifferent alkyl substituents on the phenyl groups.

The stabilizer mixture is usually comprised of between about 15 andabout 90 percent and preferably between about 25 and about percent byWeight of the dialkyl diphenyl amine. There appears to be a synergisticeffect when the butylated hydroxy toluene is admixed with the ..mine inthese proportions since these mixtures are more efiective than when thesame amount of butylated hydroxy toluene or the amine is usedseparately.

The proportion of the stabilizer mixture employed is usually betweenabout 10 and about 50,000 and preferably between about 500 and about5,000 parts per million of the polyether polyol. More preferably, theproportion of stabilizer mixture employed is in the range between about2,000 and about 4,000 parts per million of polyether polyol. In order toobtain the maximum benefit of the stabilizer mixture, it is preferablyadmixed with the polyether polyol prior to employing the polyol in thepreparation of urethane foams. However, when degradation of thepolyether polyol is not a problem, the stabilizer mixture can be addedwith the other reactants when preparing the polyurethane foam. Theproportion of the stabilizer mixture, when employing the lattertechnique, is still based upon the proportion of polyether polyol asdescribed above.

Polyether polyols which are stabilized in accordance with the process ofthis invention include the reaction product of a 1,2-oxide with analiphatic polyhydric alcohol containing between about 2 and about 6hydroxyl groups, and between about 2 and about 8 carbon atoms permolecule. Suitable compounds useful in' preparing these polyetherpolyols include lower alkylene oxides containing between about 2 andabout 8 carbon atoms, such as ethylene oxide, propylene oxide, butyleneoxide, cyclohexene oxide, and glycidol. Mixtures of these 1,2- oxidesare also useful in preparing polyether polyols which can be stabilizedby the technique of this invention. The polyether polyol may be formedby known techniques in which an aliphatic polyhydric alcohol or compoundis reacted with a single 1,2-oxide or a mixture of two or more of the1,2-oxides. If desired, the alcohol may be first oxyalkylated with one1,2-oxide, followed by oxyalkylation with a different 1,2-oxide or amixture of 1,2-oxides. If desired, the resulting oxyalkylated alcoholthen can be further oxyalkylated with a still different 1,2-oxide.

For convenience, the term mixture, when applied to a polyether polyolcontaining a mixture of 1,2-oxides,

p,p'-dipropyl diphenyl amine p,p'-diamyl diphenyl amine p,p'-dihexyldiphenyl amine p,p'-dioctyl diphenyl amine p,p-didodecyl diphenyl aminep,p'-ditetradecyl diphenyl amine p,p'-dioctodecyl diphenyl amine isintended to include both random and/or block polyethers such as (1)random addition obtained by simultaneously reacting two or more1,2-oxides with the polyhydric compound,

(2) block addition in which the polyhydric compound is first reactedwith one 1,2-oxide and then reacted with a second 1,2-oxide.

(3) block addition (2) followed by random addition (1) or an additionalblock of 1,2-oxide.

Any suitable ratio of different 1,2-oxides may be employed. When amixture of ethylene oxide and propylene oxide are utilized to formpolyethers by random and/ or block addition, the proportion of ethyleneoxide is generally between about 3 and about 60, and preferably betweenabout 5 and about 50 weight percent of the mixture.

Aliphatic polyhydric alcohol reactants in the polyether polyol are thosecontaining between 2 and about 6 hydroxyl groups and between 2 and about8 carbon atoms per molecule, as illustrated by compounds such as thefollowing: ethylene glycol, propylene glycol, 2,3-butylene glycol,1,3-butylene glycol, 1,5-pentane diol, 1,6- hexene idol, glycerol,trimethylolpropane, sorbitol, pentaerythritol, mixtures thereof and thelike. In addition, cyclic aliphatic polyhydric compounds such as starch,glucose, sucrose, methyl glucoside and the like may also be employed inthe preparation of the polyether polyol. Each of the aforesaidpolyhydric com pounds and alcohols can be oxyalkylated with ethyleneoxide, propylene oxide, butylene oxide, cyclohexene oxide, glycidol, ormixtures thereof. For example glycerol is first oxyalkylated withpropylene oxide and the resulting polyether polyol is then oxyalkylatedwith ethylene oxide. Alternatively, glycerol is reacted with ethyleneoxide and the resulting polyether polyol is reacted with propyleneoxide. If desired, each of the resulting polyethers can be furtherreacted with an mixture of propylene oxide and ethylene oxide. Each ofthe above-mentioned polyhydric compounds can be reacted with mixtures ofethylene oxide and propylene oxide or any two or more of any of theaforesaid 1,2-oxides, in the same manner. Techniques for preparingsuitable polyethers from mixed 1,2-oxides are shown in US. Pat. No.2,674,- 619 issued to Lunsted on Apr. 6, 1954; US. Pat. No. 2,733,272,issued to Horsley et al., on Jan. 31, 1956; US. Pat. No. 2,831,034,issued to Pruitt et al. on Apr. 15, 1958; US. Pat. No. 3,036,118, issuedto Jackson et al. on May 22, 1962; US. Pat. No. 2,948,757, issued toPruitt et. al. on Aug. 9, 1960. All of these polyether polyols can bestabilized in accordance with the process of the invention.

Sufiicient alkylene oxide is added to the polyhydric alcohol to providea molecular weight in the range of between about 200 and about 10,000,and preferably between about 250 and about 8000.

Polyether polyols containing the above-mentioned stabilizer mixture inthe above-mentioned proportions may be used as lubricants, heat transferfluids, hydraulic fluids, surface active agents, and the like but arepreferably employed as a reactant in the prepartion of polyurethanefoams.

An organic polyisocyanate may be employed in the preparation of thepolyurethane foams. This includes diisocyanates, triisocyanates, andpolyisocyanates. Naturally the organic diisocyanates are preferred dueto commercial availability, especially mixtures of isomers of tolylenediisocyanate which are readily available commercially. The most commonisocyanate available is tolylene diisocyanate, which is a mixture ofabout 80 percent by weight of 2,4-tolylene diisocyanate and about 20percent of the 2,6-isomer. Other typical isocyanates include, but arenot limited to, the following: 4,4'-methylene-bis-(phenylisocyanate),3,3 bitolylene-4,4'-diisocyanate, 3,3'-dimethoxy-biphenylene 4,4diisocyanate, naphthalene 1,5 diisocyanate, hexamethylene diisocyanate,1,4-phenylene diicosyanate, polyphenylene polymethylene isocyanate, etc.The amount of isocyanate employed in the preparation of the polyurethanefoams should be sufficient to provide at least about 0.7 NCO groups perhydroxyl group present in the reaction system. This includes the numberof hydroxyl groups present in the polyether polyol, the number ofhydroxyl groups in any additive employed, and the number of hydroxylgroups employed in the foaming agent. An excess of isocyanate compoundmay be conveniently employed; however, this is generally undesirable dueto the high cost of the isocyanate compounds. It is preferable,therefore, to employ no greater than about 1.5 NCO groups per hydroxylgroup, and preferably between about 0.9 and 1.3 NCO groups per hydroxylgroup.

The polyurethane foams are prepared in the presence of a foaming agent,reaction catalyst, and preferably a small proportion of a surfactant.The foaming agent employed may be any of those known to be useful forthis purpose, such as water, which is preferred, the halogenatedhydrocarbons, and mixtures thereof. Typical halogenated hydrocarbonsinclude, but are not limited to, the following:monotluorotrichloromethane, difluorodichloromethane,1,1,2-trichloro-1,2,2-trifiuoroethane, methylene chloride, chloroform,and carbon tetrachloride. The amount of foaming agent employed may bevaried within a wide range. Generally, however, the halogenatedhydrocarbons are employed in an amount from 1 to 50 parts by weight perparts by weight of the polyether polyol, and generally water is employedin an amount of from 0.1 to 10 parts by weight per 100 parts by weightof the polyether polyol.

The polyurethane foams are prepared in the presence of a catalyticamount of a reaction catalyst. The catalyst employed may be any of thecatalysts known to be useful for this purpose, or mixture thereof,including tertiary amines and metallic salts. Typical teritary aminesinclude, but are not limited to, the following: N-methyl morpholine,N-hydroxyethyl morpholine, tri ethylene diamine, dimethyl ethanol amine,tetramethylbutane diamine, triethylamine and trimethylamine. Typicalmetallic salts include, for example, the salts of antimony, tin andiron, e.g., dibutyltin dilaurate, stannous octoate, etc. Generallyspeaking, the catalyst is employed in an amount from 0.1 to 2.0 percentby weight of the polyether polyol.

Various additives may be employed in the preparation of polyurethanefoams in order to achieve particular properties. Typical additivesinclude, but are not limited to, the following: monocarborylic acids,polycarboxylic acids, polyesters, monohydroxy compounds, polyhydroxycompounds, etc.

It is preferred in the preparation of the polyurethane compounds of thepresent invention to employ minor amounts of a surfactant in order toimprove the cell structure of the polyurethane foams. Typical of suchsurfactants are the silicone oils of the type disclosed in US. PatentNo. 2,834,748 issued May 13, 1958, to Donald L. Bailey et al. and in abook Rigid Plastics Foams by T. H. Ferrigno (1963), Reinhold PublishingCompany, especially pages 40-42. Other suitable compounds useful assurfactants include synthetic detergents such as oxyethylated nonylphenol and other ethylene oxide and glycidolbased surfactants. Generallyup to 2 parts by weight of the surfactant is employed per 100 parts ofpolyether polyol.

Various additives can be employed which serve to provide differentproperties, e.g., fillers, such as clay, calcium sulfate, bariumsulfate, or ammonium phosphate may be added to lower cost and improvephysical properties. Ingredients such as dyes may be added for color,and fibrous glass, asbestos, or synthetic fibers may be added forstrength. In addition, plasticizers, dcodorants and other anti-oxidantsmay be added.

Either the one-shot technique, the prepolymer technique or thequasi-prepolymer technique may be employed to prepare the polyurethanefoams of this invention.

The proportion of stabilizer mixture necessary to stabilize thepolyether polyol to 50,000 parts per'million of polyether polyol) isgenerally sufiicient to stabilize the resuting foam against scorch.Thus, if the stabilizer mixture is not present in the polyether polyolused in the foam preparation, it may be added in the above definedproportions during the foaming reaction in order to produce a foaminhibited against scorch. Addition of this stabilizer mixture may bemade as a concentrated solution in a portion of the polyether polyol, oras a slurry or solution in one of the other suitable liquid streams,such as the silicone surfactant.

The following examples are presented to illustrate the invention morefully without any intentions of being limited thereby. All parts andpercentages are by weight unless otherwise specified.

EXAMPLES 1-7 A sample of oxypropylated glycerol having a molecularweight of 3,000 was divided into 9 portions identified as Portions A-I.Portions A-G were each admixed with a mixture of butylated hydroxytoluene and p,p-dioctyl diphenyl amine. The composition of the novelstabilizer mixture used to stabilize each portion is set forth below inTable I as Examples 1-7. Portions H and I were mixed with a commercialstabilizer containing butylated hydroxy toluene. These portions areidentified as Comparative Tests C1 and C-2 in Table I.

After admixing Portions A-G of the polyether polyol with the stabilizermixture, and Portions H and I with the commercial stabilizer containingbutylated hydroxy toluene, each portion was placed in a Perkin-Elmerdifferential scanning calorimiter, Model DSC-l, to determine thetemperature of transition, T (which is the temperature of the initiationof oxidative decomposition) of the resulting stabilized polyetherpolyol. In the operation of this apparatus the sample to be tested wasplaced in an aluminum cup and heated along with a reference cup at aprogrammed rate (approximately C. per minute) and the power necessary tokeep both the sample and the reference material at a programmedtemperature was recorded on the Y axis of the time-base recorder. At atransition of the sample the power difference supplied to each sampledue to absorption or emission of energy by the sample was noted by adeflection in the recorder. The transition temperature was usuallydetermined by locating the point of interception of the base line andthe slope of the deflection. The higher the transition temperature ofthe sample the more stable was the sample.

TABLE I Parts per Parts per million of million of butylated p,p.dioctylTransition hydroxy diphenyl tempera- Portion toluene amine ture, C

It can be seen from the table that portion H, which contained nostabilizer mixture of this invention degraded at a substantially lowertemperature than the portions which were treated with the stabilizingproportions of the mixtures of this invention. The table also shows thatthe use of only butylated hydroxy toluene (portion I) in the same totalquantity of stabilizers as portions A through G also resulted indegradation at a temperature below about 200 C.

6 EXAMPLES 8-14 The procedure of Examples 1-7 was repeated with theexception that different proportions and different ratios of thebutylated hydroxy toluene and amine were employed to stabilize theoxypropylated glycerol of Examples l-7. The transition temperature ofthese examples are presented in Table II below.

EXAMPLES 15-22 Polyurethane foams were prepared from the oxypropylatedglycerol of Example 6 containing 3700 p.p.m. of a stabilizer mixture ofbutylated hydroxy toluene and p,p-dioctyl diphenyl amine in a ratio of2500 parts of butylated hydroxy toluene per 1200 parts of the amine. Inpreparing each foam 100 parts of the stabilized polyether polyol wasplaced in a container, followed by the addition of 2.0 parts of siliconesurfactant, 0.4 part of triethylene diamine and 4 parts of water. Thismixture was stirred at 5000 r.p.m. for 10-20 seconds and 0.2 part ofstannous octoate catalyst was added with a syringe. After an additionall0-20 seconds, the stirrer speed was reduced to about 3500 r.p.m., andthe tolylene diisocyanate was then added all at once from a container.In Examples 15-22, the quantity of tolylene diisocyanate was varied overan isocyanate index range from 90 to 130 (the isocyanate index being thepercent of the stoichiometric quantity of NCO groups in the isocyanaterequired to react with all of the hydroxyl groups present in themixture).

After seven seconds of reaction in the container, the contents werepoured into a 12" x 12" cardboard box. After completion of the rise, thefoams were post-cured at 100 C. for 10 minutes. Vertical blocks 1" thickx 6" x 6" were cut from near the center of each foam in each box, thenwrapped in aluminum foil and placed in an oven at 375 F. for a period of3 hours. In addition, samples of each of the foams were evaluated in thediffer ential scanning calorimeter as described in Examples 1-7, and thetransition temperature of the foam was determined. Presented below inTable III is the transition temperature for each of the foams preparedwith various iso- 244. 5 245. 5 242. 0 247. 5 2&4. 5 246. 5 240. 0

Each of the foams, after being removed from the 375 F. oven, was white,and no significant discoloring was observed.

For purposes of comparison a similar formulation was 75 employed inmaking a flexible urethane foam except that only conventional stabilizercomponents were contained in the Oxypropylated glycerol. Large bunshaving a height of about 30 each were stacked in groups of 9 buns. Thetemperature of the center bun reached as high as 300 F. and remainedabove about 250 F. for a period of about 29 Propylene glycol initiatorreacted first with ethylene oxide and then topped with propylene oxide,the ethylene Oxide being 40 percent 16 hours. Buns stored in thismanner, without employing and the propylene oxide being 60 a stabilizersystem of this invention were scorched in the percent of the totalalkylene oxide. center and had a brown appearance. The molecular weightof the re- For purposes of further comparison, similar polyuresultingpolyether was approximatethane foam buns were made, utilizing thestabilizer mix- 10 1y 2670. fi Egamples gg Each of the above polyetherswas divided into two W en t e um were S ore m1 er ese co 1 1o portions,and each portion Was admixed with either 3700 parts per million ofbutylated hydroxy toluene, or a mix- EXAMPLES 23 29 ture of 2500 partsof butylated hydroxy toluene and 1200 15 parts of p,p'-dioctyl diphenylamine. Each portion was The Procedure of Example 1 Was repeated Wlth thetested to determine the transition temperature in ac- P that theOxypropylated glycerol Was replaced cordance with the procedure ofExample 1. With one ofthe followlng p y Presented below in the table arethe transition tem peratures for each portion, and the delta T theincrease Examples: Polyether polyol description in the transitiontemperature resulting from the synergis- 23 Oxypropylatedpentaerythritol havtic combination of butylated hydroxy toluene andp,p'- ing a molecular weight of approxldioctyl diphenyl amine forpolyethers stabilized in acmately 4000. cordance with theaboveprocedure:

Transition tempera ture, 0

2,500 p.p.m. BHT" 3,700 plus p.p.m. 1,200 p.p.m. Polyol type BHT* DDA ATExample:

23 Oxypropylated pentaerythritol 196.3 217.3 21.0 24 Oxypropylatedpropylene glycol 100. 3 210. 3 25. 7 25 Oxypropylated glycerol toppedwith eth- 196. 5 217. 3 21.8

ylene oxide (3,000 molecular weight). 20 Oxypropylated glycerol toppedwith eth- 106. 1 216. 3 20. 2

yleue oxide (4,000 molecular weight). 27 Random ethylene oxide andpropylene 196.0 219.0 23.0

oxide adduct of glycerol. 28 Oxyethylated pentaerythritol topped with195.3 217.5 22.2

propylene oxide. 29 Oxyethylatcd propylene glycol topped 190.0 215.325.3

with ethylene oxide.

*BHT= Butylated hydroxy toluene. "DDA p,p-dioctyl diphenyl amine.

24 Oxypropylated propylene glycol having a molecular weight ofapproximately 2000.

25 Glycerol initiator first reacted with propylene oxide to a hydroxylnumber of 60.5, and then topped with 5 moles of ethylene oxide. Themolecular weight of the polyether was approximately 3000.

26 Glycerol initiator first reacted with propylene oxide to a molecularweight of 3730, and then topped with 5 moles of ethylene oxide. Themolecular weight of the polyether was approximately 4000.

27 Glycerol initiator is reacted with a mixture of ethylene oxide andpropylene oxide in a ratio of approximately 18 percent ethylene oxide to82 percent propylene oxide by weight to form a polyether having amolecular weight of approximately 4000.

28 Pentaerythritol initiator reacted first with ethylene oxide and thentopped with propylene oxide, the ethylene oxide representing percent andthe ethylene oxide representing 60 percent of the total alkylene oxide.The resulting polyether had a molecular weight of approximately 5340.

These data show that when 1200 parts of butylated hydroxy toluene werereplaced with an equivalent weight of p,p'-dioctyl diphenyl amine toform a total stabilizer content of 3700 parts per million, thetransition temperature was sharply increased for each of the polyolstested, thereby showing the stabilizing effect of this mixture.

EXAMPLES 3036 Each of the polyethers of Examples 23-29 containing 2500parts per million of butylated hydroxy toluene and 1200 parts ofp,p'-dioctyl diphenyl amine, were used in the preparation ofpolyurethane foams by reacting each polyether with tolylene diisocyanatein the presence of basic catalyst, a surfactant and foaming agent. Eachof the resulting foams was free from scorch when subjected totemperatures of between about 250 to 300 F. for a period of about 16hours.

Various modifications of the invention, some of which have been referredto above, may be employed without departing from the spirit of theinvention.

What is desired to be secured by Letters Patent is:

1. A. polyurethane foam composition stabilized against scorch comprisedof a polyurethane foam prepared by reacting (1) an organicpolyisocyanate with (2) a polyether polyol comprised of the reactionproduct of (a) a 1,2-oxide and (b) an aliphatic polyhydric alcoholcontaining between 2 and 6 hydroxyl groups and between 2 and 8 carbonatoms per molecule, in the presence of (A) a reaction catalyst, (B) afoaming agent, and (C) a scorch preventing proportion of a mixture of(I) 2,6-ditertiary-butyl-4-methyl-phenol, and (II) a p,p-dialkyldiphenyl amine,

(i) wherein said alkyl contains between about 3 and about 18 carbonatoms,

and (ii) the proportion of said amine is between about and about 90percent by weight of said mixture.

2. The composition of claim 1 wherein the proportion of said amine isbetween about 25 and about 85 percent by weight of said mixture, andsaid alkyl contains between about 6 and about 10 carbon atoms.

3. The composition of claim 2 where the scorch preventing proportion isbetween about 10 and about 50,000 parts per million of said polyetherpolyol.

4. The composition of claim 2 wherein said amine is p,p'-dioctyldiphenyl amine.

5. The composition of claim 4 wherein the scorch preventing proportionis between about 500 and about 5000 parts per million of said polyetherpolyols.

6. The composition of claim 2 wherein said polyether polyol is thereaction product of a 1,2-oxide with an aliphatic polyhydric compound,

(1) said 1,2-oxide being selected from the group consisting of ethyleneoxide, butylene oxide, propylene oxide, cyclohexene oxide, glycidol andmixtures thereof, and

(2) said polyhydric compound being selected from the group consisting ofethylene glycol, propylene glycol,

10 2,3-butylene glycol, 1,3-butylene glycol, 1,5-pentane diol,1,6-hexene diol, glycerol, trimethylolpropane, sorbitol,pentaerythritol, starch, glucose, sucrose, methyl .glucoside, andmixtures thereof. 7. The composition of claim 6 wherein said 1,2-oxideis propylene oxide.

8. The composition of claim 7 wherein said polyhydric compound ispentaerythritol.

9. The composition of claim 7 wherein said polyhydric compound isglycerol.

10. The composition of claim 7 wherein said polyhydric compound ispropylene glycol.

11. The composition of claim 6 wherein said 1,2-oxide is a mixture ofethylene oxide and propylene oxide.

12. The composition of claim 11 wherein the proportion of ethylene oxideis in the range of between about 3 and about percent by weight of saidmixture.

References Cited UNITED STATES PATENTS 2,687,377 8/1954 Stewart et al252-51.5 2,915,496 12/1959 Swart et a1. 26045.7 2,938,058 5/1960 Tinsleyet al 2606115 2,942,033 6/1960 Leis et al 2606ll.5 3,072,605 1/1963Rogers et al 2604595 3,194,773 7/1965 Hostettler 2602.5 3,325,547 6/1967Cour et a1. 260-611.5 3,437,694 4/1969 Austin 2606ll.5 3,452,056 6/ 1969Sundholm 260-390 HOSEA E. TAYLOR, Primary Examiner H. S. COCKERAM,Assistant Examiner U.S. Cl. X.R. 26077.5

